Air dryers are commonly used to remove moisture from a compressed air stream so that a minimum of moisture is introduced into the devices powered by the compressed air. Moisture can have a detrimental impact on such downstream devices, such as ice blockage, rust, and lack of proper lubrication. It is highly important in a compressed air system to provide the driest air possible to the downstream devices, and is critical for the safe and proper operation of locomotives and rail cars.
There are several designs of air dryers used on locomotives today, and a regenerative desiccant air dryer is the most common. The periodic replacement of the drying agent is a required maintenance procedure, and can be a difficult, messy, and wasteful process with prior art dryers, since in some types the drying agent is poured loosely into the dryer tanks. Other prior art dryers offer cartridges that have the drying agent contained within them, but these cartridges must be made to exacting tolerances so that the wet air does not pass around the cartridge. This makes the cartridge more difficult and expensive to manufacture, but eases the maintenance process.